JP2018507978A - Flow control actuator for reciprocating compressor - Google Patents

Abstract

An electromechanical actuator (9, 9 ', 9 ", 9"') for controlling the discharge amount of the reciprocating compressor, which cooperates with the intake valve (3) of the reciprocating compressor at one end. And at the other end a movable rod (12, 12 ') designed to cooperate with a movable element (18) of magnetizable material and at least one chamber (17) containing said movable element (18) And at least one coil (29, 29 ′) of an electromagnet disposed in a seat (28) facing the chamber (17) protrudes over the chamber (17), and the coil (29, 29 ′) ) And the chamber (17), at least one protective element (30, 30 ′, 30 ″) made of a non-magnetic material is disposed, and the protective element (30, 30 ′, 30 ″) Static sealing element In the actuator, which is designed to keep the electromagnet coils (29, 29 ') away from the chamber (17) containing the movable elements (18), the actuators (31, 32) are made of nonmagnetic material. The protective element (30 ″) comprises at least two sets of static sealing elements (31, 32), the first set being arranged on the inner side with respect to the protective element and the second set with respect to the protective element Located on the outside, gas recovery holes (42, 42 ') are provided between the set of static sealing elements, and at least one hole (35) is connected to the chamber (23 for connection to the gas bleed and flush circuit. Electromechanical actuators (9, 9 ', 9 ", 9"').

Description

  The present invention relates to an actuator for controlling the discharge amount of a reciprocating compressor, particularly a reciprocating compressor, more specifically, an electromechanical actuator for performing continuous return flow control of an intake valve of a reciprocating compressor, The present invention relates to an electromechanical actuator capable of controlling an intake valve for each compression cycle.

  Return flow control is one of the known systems of reciprocating compressor flow control and is performed by delaying the closing of the intake valve relative to the closing point at maximum flow. The gas entering the compressor cylinder flows back through the suction pipe by an amount proportional to the length of the compression stroke while the intake valve is open.

  It should be pointed out in the following description that reference is made to “dynamic” seals, washers, sealing elements as well as “static” seals, washers, sealing elements. The term “dynamic” sealing element means a sealing element in which the sealing element is placed between two parts and wears as one part moves, and thus is subject to friction and dynamic wear. An element, while a “static” sealing element means a sealing element located between two fixed parts and thus is not subject to wear caused by movement.

  Most recently, several different return flow control devices for reciprocating compressors, consisting of electromagnetic actuators, have been implemented in the prior art, and such prior art includes a continuous control for reciprocating compressors. Applicant's WO 2008/000698 concerning apparatus, US 7,651,069 concerning valve with electromagnetic actuator, US 2012/0260796 concerning reciprocating compressor with controlled discharge amount, method for controlling reciprocating compressor discharge amount and discharge amount control WO 2011/119879 relating to an improved reciprocating compressor is included.

  Normally, electromagnetic regulators are equipped with actuator rods that cooperate with compressor intake valves and electromagnets that move movable elements that cooperate with each other, and can be operated using various gases at various pressures. Many of these gases must be refined, and most of these gases are refinery gas, etc., which are extremely flammable.

  One of the main problems to be solved in such a device is to prevent compressed gas coming in from somewhere and coming into contact with related electronic devices such as electromagnet coils and movable element position sensors. A mixture of atmospheric oxygen and flammable gas can explode when it comes into contact with an electric ignition source.

  State of the art, such electromechanical actuators, and more commonly all actuators used in reciprocating compressors, have dynamic seals placed on the actuator rods, whether pneumatic or hydraulic. An example is the reciprocating compressor provided and described in US 2010/0086415.

  Unlike normal actuators used for return flow control with stepwise flow control, actuators used for return flow control that can perform continuous flow control have a very high operating frequency, for example compression rotating at 600 rpm. The machine needs to operate the actuator approximately 315 million cycles in a year with continuous return flow control, which means that the actuator armature and associated rod are moved down 315 million times, It is sufficient to think that it is necessary to move up the same number of times. Since the rod of the actuator slides in the associated seat where the annular sealing element is located, one of the biggest problems with this type of actuator is the wear of such a sealing element, storing the armature There is a risk that the compressed gas may enter the chamber and come into contact with the electromagnet coil of the actuator.

  To reduce the risk of compressed gas flowing back into the chamber, especially when the rod seal is worn, use a system to collect the gas through the rod, and the nitrogen barrier or similar to reduce the risk Although it is known to use an inert gas barrier, these have not proven to be effective at all.

  Although the actuator rod slides along such a sealing element, the sealing element may also be damaged by impurities and metal particles that may be present in the compressed gas.

  Furthermore, unlike pneumatic or hydraulic actuators, electromechanical actuators are highly flammable gases such as hydrogen and ethylene due to gas leakage from the actuator rod when the rod's dynamic sealing element is damaged. More broadly, in the case of various hydrocarbons, if the gas enters the chamber containing the electromagnet, the safety risk of the entire compressor increases.

  As is well known, in order to prevent the intrusion of compressed gas that affects the coil of the electromagnet, resin processing is performed, but this resin processing is not sufficient to ensure that the compressed gas does not enter. Also, it should be considered that air may be left inside or under the resin processing, and gas intrusion may endanger not only the actuator but also the compressor itself. In fact, it should be remembered that the operation of the reciprocating compressor can be performed at various pressures and the intake pressure can exceed 100 bar.

International Publication No. 2008/000698 U.S. Pat. No. 7651069 US Patent Application Publication No. 2012/0260796 International Publication No. 2011/119879 US Patent Application Publication No. 2010/0086415

  One object of the present invention is to overcome the drawbacks and problems of the known actuators and systems described above, an actuator for continuous return flow control of the reciprocating compressor discharge, that is, the intake valve in each compression cycle. Actuators that can act, and therefore safer, balanced, reliable, actuators applicable to conventional automatic intake valves of reciprocating compressors, and therefore very safe and particularly highly combustible Actuators that are safe when used in environments with high gas content and are advantageous from the viewpoint of pressure compensation, that is, effective from the viewpoint of limiting friction between various moving parts, balanced from the viewpoint of internal pressure Is to provide a simple actuator.

  This object and other objects are achieved according to the invention by an actuator for controlling the discharge rate of a reciprocating compressor according to claim 1. Advantageous further features are described in the dependent claims.

  According to a first aspect of the invention, an electromechanical actuator for controlling the discharge rate of a reciprocating compressor cooperates with at least one intake valve of the reciprocating compressor at one end and is magnetizable at the other end A movable rod designed to cooperate with the movable element, and at least one chamber in which the movable element is accommodated and at least one electromagnet is opposed, and the coil of the electromagnet is disposed in the chamber. At least one protective element made of a non-magnetic material is arranged between the coil and the chamber, the static sealing element is provided on the protective element, and the movable element It is characterized in that the coil of the electromagnet can be kept away from the chamber containing the magnet.

  Advantageously, the electric of the present invention for continuous return flow control of the discharge of a reciprocating compressor comprising at least one non-magnetic protective element for an electromagnet coil and provided with at least one static seal. Mechanical actuators are very reliable, safe, efficient in terms of friction of moving parts, and very balanced in terms of the resulting pressure.

  By using static sealing elements instead of or in addition to the dynamic seal provided on the rod, a higher level of safety, especially when handling flammable gases such as refinery gas Can provide sex.

  By using a nonmagnetic protective element, the coil of the electromagnet can be protected without affecting the generated magnetic field. This is because the nonmagnetic element closes the magnetic field generated by the electromagnet on the armature and does not close it on the nonmagnetic element.

Furthermore, by using non-magnetic elements, the dynamic seal can be completely eliminated in another configuration of the control actuator of the present invention. This alternative electromagnetic actuator configuration can provide additional benefits to the system without the use of dynamic seals. First, as one of the most important points of the system, the high reliability of the system is expressed by eliminating the dynamic seal. Yet another configuration provides a second substantial advantage. By eliminating the dynamic seal placed on the rod, the moving parts are placed in the same environment and the pressure on the movable element or armature cancels each other,
A well-balanced system can be obtained. Thus, by eliminating the dynamic seal, a balanced system can be obtained without resorting to complex pressure compensation systems such as those described in US 7,651,069.

  Another negative aspect due to the presence of dynamic washers on the actuator rod is related to friction, as described above. Thus, the presence of non-magnetic means fitted with static seals arranged to protect the electromagnet coils can ensure a higher level of safety and higher reliability of the entire system.

  Furthermore, the actuator of the present invention can be further provided with a non-magnetic and non-conductive element in the region where the electrical position sensor is provided, so that the gas in the chamber below the sensor is transferred to the electrical component of the sensor. Contact can be prevented.

  The chamber in which the sensor is located can be provided with at least one hole connecting the chamber to the bleed circuit. As is known, compressors that compress explosive gases perform a scrub cycle with nitrogen to remove air from the compressor prior to starting. During this cleaning cycle any remaining air in any chamber needs to be removed. By using a hole connected to a bleed circuit controlled by a valve, any leftover air can be exhausted from the chamber during the compressor cleaning operation.

  The non-magnetic protective element of the electromagnet coil is generally a simple annular shape, or the protective element made of non-magnetic material has a first inner ring and a second outer ring to hold it in place. A ring may be provided. Such rings are preferably coaxial with each other and connected by suitable spokes.

  The actuator of the present invention may further comprise mechanical means for connecting the intake valve pusher rod to the actuator rod. The purpose of this measure is to increase the reliability of the system, in particular to avoid wear occurring in the contact area between the two rods and not to rely on complex play compensation systems. In a preferred configuration, the intake valve is inserted into the compressor cylinder housing and locked in place with a valve cover. Next, the flanged body into which the electromechanical actuator is inserted is connected to the valve cover. By means of a suitable cover and a suitable tool present on the flanged body, the mechanical means are screwed together to bring the two rods together.

  Additional features and advantages of the present invention will be better understood by the following description, given by way of non-limiting illustration and with reference to the accompanying drawings.

FIG. 1 is a cross-sectional view of a first embodiment of an electromechanical actuator for controlling the discharge amount of a reciprocating compressor according to the present invention, provided with opposing electromagnets, and a first embodiment of a nonmagnetic protective element. is there. FIG. 2 is an enlarged view of the electromechanical actuator of FIG. FIG. 3 is a perspective view showing one of the nonmagnetic elements used in the actuator of FIGS. 1 and 2. 4 is a cross-sectional perspective view of the nonmagnetic element of FIG. FIG. 5 is a perspective view showing a modified example of the embodiment of the nonmagnetic protective element. 6 is a cross-sectional perspective view of the nonmagnetic element of FIG. FIG. 7 shows a second embodiment of the actuator of the present invention, which includes a modification of the embodiment of the nonmagnetic protection element shown in FIGS. 4 and 5. FIG. 8 is a further cross-sectional view of the actuator of FIG. 7, with the associated rods connected by mechanical means to the rods of the reciprocating compressor intake valve pushers. FIG. 9 is a cross-sectional view of a further modification of the actuator of the present invention, in which a single electromagnet is provided. FIG. 10 is a cross-sectional view of a further modification of the actuator of the present invention, in which a gas recovery hole is provided at a position corresponding to the nonmagnetic protective element. FIG. 11 is a cross-sectional view of an actuator intended for use with a bellows having one end integral with the actuator lower body and the other end integral with the actuator rod.

  With reference to the accompanying drawings, in particular FIGS. 1 and 2, reference numeral 1 designates a cylinder of a reciprocating compressor (partially indicated), which may be single-acting or double-acting, with a piston 2 therein. Slides. An opening 101 is provided in the wall of the cylinder for storing the intake valve 3. The suction chamber 203 communicates the suction pipe 501 with the chamber 502 and compresses the fluid in the chamber 502. The valve 3 is locked in the cylinder 1 by a cover 303. The intake valve 3 mainly includes a valve seat 903 having a duct 113 for passing gas, an opposite seat 103 having a duct 503 for passing gas, an elastic load means 603, and at least one sealing element 703. And a pusher 4 that slides in the axial direction with respect to the opening 101 in order to act on the closing device 703 via the leg 104 and push the valve 3 to the open position. A portion of the cover 303 opposite to the portion facing the cylinder chamber 502 is provided with an axial hole 8 into which the electromechanical actuator 9 is inserted and fastened to the cover 303 by the pin 11. The The rod 12 of the actuator 9 is slidable in the axial direction within the body 209 of the actuator and is guided by the guide element 13. The lower end of the rod 12 of the actuator 9 abuts on the upper end of the rod 7 of the pusher 4. A sealing element 14 is provided in the body 209 of the actuator, which is housed in a suitable seat made in the body 209 and with the rod 12 that translates in contact with the sealing element. Since a sealing must be ensured, it is basically a so-called dynamic sealing element. The actuator 9 is substantially composed of the lower body 209, the central body 309, and the upper body 409, which are detachably fastened to each other by appropriate pins 15. The sealing element 16 is arranged between the central body 309 of the actuator and the upper and lower bodies 209, 409. In this case, since there are no members or other elements that move while in contact with the sealing element, the so-called static element 16 is provided. Sealing element. There is a chamber 17 inside the actuator 9, in which a movable element 18 made of a magnetizable material is slidable by a guide element 19 etc. in contact with the wall of the chamber 17. The movable element or armature 18 is integral with the rod 12 of the actuator, and contacts the pair of springs 20 and 21 that attempt to hold the armature in the center position in the chamber 17 on both sides as shown in the drawing. ing. The spring 20 is arranged around the rod 12 of the actuator and contacts at one end the bottom of a suitable seat made in the lower body 209 of the actuator and contacts the lower part of the armature 18 at the other end. The spring 21 is also arranged around the rod 12 in alignment with the spring 20 and contacts the top of the armature 18 at one end and the bottom of the seat made in the upper body 409 of the actuator at the other end. ing. The rod 12 of the actuator projects from the hole 22 of the upper body 409 into the upper chamber 23, in which a position sensor 24 is provided, preferably non-magnetic, which is arranged on the upper body 409 of the actuator 9. Connected to the support element 25. This sensor 24 detects the position of the rod 12 and thus the position of the armature 18 integral therewith, and effectively controls the closed position of the intake valve 3. An element 26 made of a non-magnetic material is provided to protect the sensor 24, and a sealing element 27 is mounted so that gas in the chamber 23 does not come into contact with an electrical component to which the sensor 24 is attached. . The lower body 209 of the actuator is provided with an annular seat 28 facing the chamber 17. The seat 28 accommodates an electromagnet coil 29 and an annular protective element 30 made of a non-magnetic material. The protective element is disposed between the coil 29 and the chamber 17 and finally the electromagnet coil 29 and the movable electric machine. It is interposed between the child 18. The upper body 409 of the actuator is also provided with an annular seat 28 'that houses an electromagnet coil 29' and another annular element 30 'made of non-magnetic material to protect the coil 29'. Both non-magnetic annular elements 30 are provided with at least one inner sealing element 31 and at least one outer sealing element 32, in which case a static sealing element is advantageous. The two coils 29 and 29 'are opposed to each other in the axial direction. As can be easily guessed by looking at FIGS. 1 and 2, these annular elements 30 made of non-magnetic material are arranged between the central body 309 of the actuator 9 and the upper or lower body 409, 209 during assembly and connection. Can be inserted into. Furthermore, since the actuator 9 can be formed from these separate bodies 209, 309, 409, these non-magnetic sealing elements 30 can be easily replaced as required. By using this nonmagnetic element 30, the electromagnet coils 29 and 29 'can be protected without affecting the generated magnetic field. In fact, referring to FIG. 2, the nonmagnetic element 30 may cause the magnetic fields M, M ′ generated by the electromagnet coils 29, 29 ′ to close on the armature 18 rather than on the nonmagnetic element 30. it can. A further advantage obtained by adding a non-magnetic element 30 provided with static sealing elements 31, 32 is that the dynamic sealing element 14 on which the rod 12 slides is damaged by stress due to wear, Even if the safety of the electromechanical actuator is at risk, it is possible to guarantee excellent sealing of the actuator 9. The safety of the actuator is particularly important in the presence of highly flammable compressed gas such as hydrogen, ethylene, refinery gas, etc. The presence of the non-magnetic annular element 30 with the static sealing elements 31 and 32 attached The seal, which is not exposed to dynamic wear, thus prevents gas from penetrating into contact with the electromagnet coils 29, 29 '. In order to further limit the possibility that the gas present in the suction chamber 203 reaches the chamber 17 in which the armature 18 is moving, a first radial hole 33 for collecting the gas, a nitrogen barrier gas, A second radial hole 34 for supply is provided in the main body 209 (see FIG. 1).

  FIGS. 3 and 4 of the accompanying drawings show one of the two annular elements 30 made of a non-magnetic material as described with reference to FIGS. The annular element 30 is formed by a wider first inner ring 130 and a narrower second peripheral ring 330 connected by spokes 230. The inner ring 130 and the outer ring 330 are coaxial. The spokes 230 connecting the inner ring 130 to the outer ring 330 are preferably the same length and are evenly spaced. The inner ring 130 is provided with a first inner annular seat 430 for accommodating the sealing element 31 shown in FIG. 2 and a second outer annular seat 530 for accommodating the sealing element 32 shown in FIG. Yes. The purpose of the outer annular element 330 is when the annular sealing element 30 is placed between the actuator bodies shown in FIG. 2, that is, between the upper body 409 and the central body 309 or between the central body 309 and the lower body 209. It is in keeping the ring 130 firmly in place.

  5 and 6 show a modified example in which the annular element 30 'made of a nonmagnetic material is simplified. Essentially in this variation, the sealing element includes a single ring 130 ′ with an inner sealing element within the annular housing seat 430 and an outer sealing element outside the annular housing seat 530.

  FIG. 7 shows a modification of the electromechanical actuator 9 ′ of the present invention using the nonmagnetic annular element 30 ′ shown in FIGS. 5 and 6. Elements that have already been described with reference to the previous drawings are given the same reference numerals. These non-magnetic sealing elements 30 ′ are provided with inner and outer sealing elements 31, 32, so that the actuator 9 can be operated without the help of the sealing element 14 exposed to the dynamic wear shown in FIG. A '12 rod is provided for moving within the lower body 209. Further, a hole 35 may be provided in one of the walls of the upper chamber 23 so that the valve 36 can be connected to a circuit for extraction and nitrogen cleaning. As is known, before starting the compressor, a nitrogen wash cycle is performed to remove air from the compressor. This washing is performed to prevent the formation of an explosive mixture. During such a cleaning cycle, it is necessary to remove the remaining air from the various chambers. By utilizing the holes 35 connected to the bleed circuit and controlled by the valve 36, all the remaining air can be discharged from the chambers 23, 17, 203 during the compressor cleaning operation. A further advantage gained from the structure of FIG. 7 which is a configuration without a dynamic seal 14 is related to the instability of the armature 18 resulting from the pressure acting on the rod 12. As an example, consider the case where the diameter of the rod 12 is 20 mm and the gas pressure in the suction chamber 203 is 60 bar. If the dynamic seal 14 is on the rod 12 as shown in FIG. It is considered that about 1848 N is pushed up on the side opposite to the valve 3. Therefore, when the dynamic seal 14 is provided on the rod, the armature 18 becomes unstable, which is particularly remarkable in an actuator structure having opposing electromagnets as shown in FIG. To reduce the negative effects resulting from armature 18 instability in known regulation systems, it is necessary to rely on more than one complex pressure compensation system, but most of such systems have a pressure of compressed gas. It does not meet the conditions normally required in a fluctuating operating environment, that is, the process in which the reciprocating compressor is said to operate. Instead, in the actuator of the present invention, it is possible to eliminate such a dynamic seal by using the static sealing elements 31, 32. This ensures that in this actuator construction where the pressure in the chambers 23, 17 and 203 is the same, the armature 18 is perfectly balanced without being affected by the pressure in the cylinder chamber. This is because it can.

  FIG. 8 shows a state in which, for example, the electromechanical actuator 9 'shown in FIG. In this configuration, the rod 7 'is provided with a threaded tip 207, and this tip is screwed into a nut 38 attached to the rod 12' of the actuator 9 '. Basically, as shown in FIG. 1, the intake valve 3 is accommodated by a cover 303 in an opening 101 on the wall of the compressor, and a hollow main body 39 with a flange into which the rod 12 of the actuator is inserted is then covered with the cover 303. Mounted on. Here, the actuator 9 ′ having an associated flange is fixed to the top of the flanged main body 39 by the pin 11. An access opening 40 is provided on this side of the flanged body 39 and this opening is sealed off by a cover 41. When this cover 41 is removed, the nut 38 attached to the threaded tip 207 of the pusher rod 7 'can be tightened using a suitable tool. By using mechanical means 37, the two rods can be kept together, eliminating the wear problems that can occur on the two separate rods (12 and 7), according to US 2012/0260796 There is no need to use complex play compensation systems as described.

  FIG. 9 shows yet another modification of the electromechanical actuator 9 ″, in which only a single electromagnetic coil 29 is used, and thus the associated outer sealing element 32 and inner sealing element. It is intended to use only a single non-magnetic annular protective element 30 'provided with 31. In this case, the upper body 409 of the actuator has a through hole 22 in the center for the upper part of the rod 12. A flat portion is provided facing the chamber 17 in which the armature 18 moves.

  FIG. 10 shows yet another modification of the electromechanical actuator 9 ″ ′ of the present invention. The electromechanical actuator 9 ″ ′ includes two opposing coils 29, 29 ′ and a non-magnetic annular element 30 ″. The nonmagnetic annular element is provided with two sets of inner sealing elements 31 and two sets of outer sealing elements 32. The box-like body 409 has a first gas recovery hole 42 in the first set. Similarly, a second gas recovery hole 42 ′ is provided in the lower body 209 of the actuator with the first set of sealing elements and the second set of sealing elements. Gas recovery holes 42, 42 'are provided between the first set of sealing elements 31, 32 and the second set of sealing elements 31, 32. By the existence, very explosive Safe level when using electromechanical actuators with compressor to use easy gas is further increased.

  FIG. 11 shows still another modification of the electromechanical actuator 9 "" according to the present invention. The electromechanical actuator 9 "" is provided with a bellows 44, one end of which is integral with the actuator body 209 and the other end is integral with the enlarged portion 112 formed on the rod 12. ing.

  As can be seen from the above description, the electromechanical actuator of the present invention has various embodiments and modifications that can be used to advantage, but of course these embodiments and modifications can be combined with each other in various ways. Can do.

  In general, from a functional point of view, the electromagnetic actuator 9, 9 ′, 9 ″, 9 ″ ′ of the present invention is preferably combined in one direction by the intake valve 3, ie the action of the rod 7 or 7 ′ of the pusher 4 Since the intake valve can be opened in each compression cycle by operating in one direction by the action of the rod 12 or 12 ', the discharge flow generated by the compressor can be controlled according to the requirements of the plant. Unlike known electromechanical actuators, this actuator has the objective of providing continuous return flow control of the discharge rate in a safer, more balanced and more reliable manner.

  Therefore, the electromechanical actuator of the present invention for controlling the discharge amount of the reciprocating compressor is advantageous from the viewpoint of safety by the modification examples and combinations thereof. This is because a system for controlling the discharge amount of the reciprocating compressor is often required in a refinery that processes a highly flammable gas. Furthermore, considering that the actuator is exposed to pressure, vibration, and high temperatures, the reduction in electrical insulation is sufficient to generate a spark, a source of ignition that ignites the gas. By using a non-magnetic protective element provided with a suitable static sealing element, i.e. not subject to dynamic degradation, the safety level of the actuator is significantly improved. At the same time, the non-magnetic material constituting the protective element allows the electromagnet coil provided in the actuator to function properly and efficiently, and in fact the magnetic field continues to close on the armature.

  The electromechanical actuator of the present invention is definitely advantageous from the viewpoint of pressure compensation. The rod 12 or 12 ′ of the actuator is subjected to thrust by gas at one end, that is, the end contacting the intake valve 3. This thrust by the gas destabilizes the central position of the armature, particularly in an actuator having an opposing electromagnet. If necessary, the use of non-magnetic protective elements 30, 30 ′, 30 ″ can eliminate all sealing elements that are subject to dynamic wear as shown in FIG. Can be moved into a system that will eventually have the same pressure, ie a compensated system.

  The electromechanical actuator of the present invention has also been found to be very reliable. In fact, sealing elements that are not subject to dynamic wear, so-called static sealing elements, are preferably used. For example, a continuous return flow control of a compressor rotating at 600 rpm would require the actuator to operate approximately 315 million cycle cycles in a year, which means that the actuator armature and associated rod would be 315 It is sufficient to think that it is necessary to move down 10,000 times and move up the same number of times. It is clear that consistently advantageous reliability can be obtained by using static sealing elements and thus sealing elements that are not exposed to dynamic wear cycles.

  As a result, it has been found that the electromechanical actuator of the present invention is advantageous in that the friction between moving parts can be considerably suppressed. Sealing elements that are exposed to dynamic wear inherently produce frictional forces. The more dynamic the washer used, the greater the frictional force generated on the rod. Furthermore, the higher the pressure, the greater the frictional force. Obviously, the adjustment system must be able to operate quickly in order to ensure optimum performance. Thus, by eliminating or at least limiting so-called dynamic washers or sealing elements, the frictional force can be reduced and the actuator can be made more complete and efficient.

Claims (11)

Electromechanical actuator (9, 9 ′, 9 ″, 9 ″ ′) for controlling the discharge amount of the reciprocating compressor, which cooperates with the intake valve (3) of the reciprocating compressor at one end And at the other end a movable rod (12, 12 ') designed to cooperate with a movable element (18) of magnetizable material and at least one chamber (17) containing said movable element (18) And at least one coil (29, 29 ′) of an electromagnet disposed in a seat (28) facing the chamber (17) protrudes over the chamber (17), and the coil (29, 29 ′) ) And the chamber (17), at least one protective element (30, 30 ′, 30 ″) made of a non-magnetic material is disposed, and the protective element (30, 30 ′, 30 ″) , Static sealing elements (31 32) and is designed to keep the electromagnet coils (29, 29 ') away from the chamber (17) containing the movable element (18),
Said protective element (30 ") made of non-magnetic material comprises at least two sets of static sealing elements (31, 32), the first set being arranged inside the protective element and the second set being protected Arranged on the outside with respect to the elements, gas recovery holes (42, 42 ') are provided between the set of static sealing elements,
Electromechanical actuator (9, 9 ', 9 ", 9"'), characterized in that at least one hole (35) is provided in the chamber (23) for connection to a gas extraction and cleaning circuit.   Electromechanical actuator (9, 9 ', 9 ", 9"') according to claim 1, wherein the protective element (30, 30 ', 30 ") made of non-magnetic material has an annular shape.   Two opposing electromagnet coils (29, 29 ′) arranged on the chamber (17) side with respect to the movable element (18) are provided, and each coil (29, 29 ′) of the electromagnet includes Electromechanical actuator (9, 9 ', 9 ", 9"' according to claim 1, characterized in that an associated protective element (30, 30 ', 30 ") made of magnetic material is provided. ).   2. The protective element (30, 30 ') made of non-magnetic material, characterized in that it comprises at least one inner sealing element (31) and at least one outer sealing element (32). Electromechanical actuator as described (9, 9 ', 9 ", 9"').   The protective element (30) made of nonmagnetic material comprises a first inner ring (130) and a second outer ring (330), the first phosphorus and the second ring being connected by a spoke (230). Electromechanical actuator (9, 9 ', 9 ", 9"') according to claim 1, characterized in that   Electromechanical actuator (9, 9 ', 9 ", 9"') according to claim 1, comprising only static sealing elements (31, 32, 10, 16, 27).   Electromechanical actuator according to claim 1, wherein the rod (12) is designed to be connected to the rod (7) of the pusher (4) of the intake valve (3) by mechanical means (37). (9, 9 ', 9 ", 9"').   The mechanical means (37) is accommodated in a flanged body (39) removably connected to the cover (303) of the intake valve (3), and is fluid-tight to the flanged body (39). Electromechanical actuator (9, 9 ', 9 ", 9"') according to claim 7, characterized in that it comprises at least one cover (41) connected to.   In order to detect the position of the movable element (18), a sensor (24) is provided with a chamber (23) in which the sensor (24) has an associated protective element (26) made of non-magnetic material. Electromechanical actuator (9, 9 ', 9 ", 9') according to claim 1, characterized in that the protective element (26) is provided with at least one sealing element (27). 9 "').   The rod (12) comprises a body (209) in which it slides, the body (209) is fed with a first radial hole (33) for collecting gas and an inert barrier fluid, preferably nitrogen. Electromechanical actuator (9, 9 ', 9 ", 9"') according to claim 1, characterized in that a second radial hole (34) is provided.   Electromechanical actuator (9) according to claim 1, characterized in that it comprises a bellows (44) which is integral with the body (209) at one end and integral with the rod (12) at the other end. , 9 ', 9 ", 9"').

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